thought i'd jot up a few thoughts i had about realm design stuff. I've tried to make my realms as dynamic as possible (accounting for multiple paths through realms, strategic decision making, etc.) and thought i'd share a few things that might interest some.

1) Layout the map, strategic locations (citadels/manafluxes/towns/palace) and see how the marauders interact with the map. Once you get a feel for how the marauders interact with the map (usually by giving yourself a billion meta mana in an easy to reach encounter) you can see how they interact, and then decide how to place things like:
-villages: for strategic leverage when marauders come from a place you can't afford to wait by
-side quests encounters: here you can make little side narratives and rewards for players for merely making the time to make time to find these spaces. You can reward things like gold/mercs/mana/time/reverse banish/etc. to give players reasons to plan ahead and time when and what order they might tackle these things.
2)Now once all of this is in place, and you've tuned the realm just right (playing it through and ensuring the reasonable difficulty) let your imagination run wild with all of the story bits, fleshing out a nifty little narrative to give it some color.

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otherwise,
3) think in 3's: all of the encounter limits are set by 3's including:
-Encounter choices
-Encounter outcomes
-Flag/lord/merc checks

When planning this encounter stuff out in your head, keep in mind your limited to 3 things for the most part.

4) design realms as though players will play through them without help from allies. Running through realms during testing to figure out how much reinforcements spawn and keeping in mind the RNG in how they're distributed could work in your favor. Allowing players to adapt their path based on what the RNG throws out could do wonders in reducing frusteration.

Stuff like: giving rumors in towns so players can keep track of which lords getting what reinforcements, alternative paths in which to tackle the realm, and well placed villages that can come in handy when you really need them can work great for this.
Sometimes having villages placed in such a way that they give you the help you need when fighting heavily reinforced lords, while being far enough away to make it a dilemna in how many your willing to wait for work great. Even just using them as a means to spare your mercs for that final palace confontation were you most likely wont have villages.

5) Using the time limit: I feel like i can appreciate the time limit, banishing spell dynamic. When working properly, it gives you a good bit of tension, giving you incentive to not just go on auto pilot when playing the game. Though you should also give players enough hints and information about the realm's layout so that they can figure out a good playstyle to get through it in an optimal way.